A climate change expert at the United States Geological Survey was set to join Facebook’s Mark Zuckerberg in Montana last weekend to discuss the impact of global warming at Glacier National Park, but two sources with knowledge of the matter say the scientist was pulled from the visit by the U.S. Department of Interior just days before the event.

The decision has provoked suspicion from inside the USGS that the scientist’s appearance was canceled to minimize attention to the issue of climate change, according to one source.

Daniel Fagre, a research ecologist at the USGS Northern Rocky Mountain Science Center and a specialist on the impact of climate change on mountain climates, and Facebook CEO Zuckerberg were expected to meet Saturday to discuss the negative toll climate change is having on the park’s glaciers, both sources said. The sources requested anonymity because they are not authorized to speak on behalf of the department.

However, just several days ahead of the anticipated trip, according to one of the sources, Fagre’s office received word that senior officials at the Department of Interior had denied the climate scientist’s planned visit to the park.

When he pressed for answers, Fagre reportedly received little explanation — only that it was not an “approved request” from the department, according to one of the sources.

Fagre declined to comment on this story.

The USGS is one of the many bureaus of the Department of Interior, which also includes the National Park Service.

Despite the department’s decision, Zuckerberg still visited Glacier National Park, and took to his personal Facebook and Instagram pages to document his trip. He said he was joined by National Park Service rangers and wrote openly about how climate change is negatively impacting the park.

“The impact of climate change is very clear at Glacier,” Zuckerberg wrote on Facebook. “In the last hundred years, the average global temperature has risen 1.5 degrees. But in the high elevations of Montana where Glacier is the temperature is warming at three times the global average — enough to melt glaciers.”

A representative from Facebook told Mic that Zuckerberg’s team signaled that he was interested in discussing climate change at Glacier when they initially set up his trip. But the representative had no knowledge of the decision to pull Fagre and said it was the National Park Service who set up Zuckerberg’s agenda.

Heather Swift, press secretary for the Interior Department, did not address directly that the climate scientist was pulled from the visit. Instead, she sent the following written statement to Mic:

“After reviewing the event proposal which was sent to the National Park Service, the NPS and Interior made a number of park officials available for the personal tour. He was given first-class treatment by the park rangers and had the opportunity to interact with a number of park officials and Gracie the ‘bark ranger’ during his visit, which came at the height of the busy season. Allocating government funds, personnel, and resources responsibly is the definition of good government and something we are dedicated to advancing at the department.”

But according to one of the sources, some USGS employees suspect the decision may have been made to attempt to divert attention away from climate change.

Such a move by the Trump administration is not without precedent.

In May, the Department of Interior made the decision to delete a line from a study discussing the role of climate change in rising sea levels. That report was co-authored by three scientists from the USGS.

The Trump administration has also scrubbed various official references to climate change on federal government websites since taking office, including scrapping an entire section devoted to global warming on the White House website.

Mic reached out to environmentalist and founder of 350.org Bill McKibben about this story. He replied, “At every possible turn, [the Trump administration] has tried to obscure and hide the single biggest fact about the planet today, which is that it’s heating up fast.”

Zuckerberg’s visit to Glacier is part of a broader initiative by the CEO to travel to states across the country that he has never visited. In January, Zuckerberg announced a goal of visiting 30 states before the end of the year with his wife Priscilla Chan.

The drop-ins, which Zuckerberg has documented on his personal social media channels, have taken him and Chan across the United States, raising speculation in political circles that Zuckerberg may be gearing up for a run for president in the future.